Many electrical and electronic devices include current sensors for sensing current in a conductor. For example, in at least one known electricity meter, a current sensor is provided to sense current in a line conductor carrying an input current I.sub.in. A current divider divides input current I.sub.in into two currents I.sub.1 and I.sub.2, which are carried through respective resistors R.sub.1 and R.sub.2. A current comparator senses input current I.sub.2 and provides a scaled output current I.sub.out proportional to input current I.sub.in but many magnitudes lower than that of input current I.sub.in.
A known current comparator includes a current transformer having a core of magnetic material, a single turn primary winding, and first and second secondary windings which are sometimes referred to as sensing and feedback windings. Each winding has a large number of turns of fine gage wire evenly distributed around the core. The core encircles resistor R.sub.2 carrying current I.sub.2. In operation, an alternating magnetic flux from resistor R.sub.2 and produced by current I.sub.2 is induced in the current comparator transformer core. A voltage therefore is induced in the first secondary, or sensing, winding of the transformer. The signal from the sensing winding is provided to a high gain differential amplifier, and the amplifier output voltage is supplied to the feedback winding. The current in the feedback winding is the scaled output current I.sub.out. The feedback winding is configured to induce a compensating flux in the core, which reduces the alternating flux in the core toward zero. The current transformer and amplifier operate dynamically to keep the alternating magnetic flux in the core at a very low value approaching zero. As a result, the magnetizing ampere turns resulting from the measured or sensed current I.sub.2 in the single turn primary winding (formed by resistor R.sub.2) are balanced by the magnetizing ampere turns resulting from current I.sub.out in the feedback winding. This type of current sensor is sometimes referred to as an auto-zeroing toroidal current sensor. Particularly, the current comparator core is toroidally shaped, the secondary windings are toroidal windings, and the alternating magnetic flux in the core is maintained at a value approaching zero. Although this known sensor provides acceptable results, it is relatively complex and expensive.